Platform power consumption reduction via power state switching

ABSTRACT

Methods and apparatus relating to platform power consumption reduction via power state switching are described. In one embodiment, control logic causes a processor to enter a first low power consumption state (e.g., S0ix) instead of a second low power consumption state (e.g., S3) based on whether a threshold time period exists between a first wake event (e.g., corresponding to a first one of one or more awake requests) and a second wake event (e.g., corresponding to a second one of the one or more awake requests). Other embodiments are also claimed and disclosed.

RELATED APPLICATIONS

This application is a continuation and claims priority under 35 U.S.C. §120 of pending U.S. patent application Ser. No. 14/139,864, filed Dec.23, 2016, entitled PLATFORM POWER CONSUMPTION REDUCTION VIA POWER STATESWITCHING which in turn claims the benefit of an earlier filed foreignapplication Indian Patent Application No. 5444/CHE/2012 filed on Dec.23, 2012. The entire disclosure(s) of these documents are incorporatedby reference herein for all purposes.

FIELD

The present disclosure generally relates to the field of electronics.More particularly, an embodiment of the invention relates to platformpower consumption reduction via power state switching.

BACKGROUND

To reduce power consumption, some systems include processors with theability to perform at various low power (Cx) states. Each C state mayindicate a certain level of functionality and corresponding power state.For example, C0 may indicate the processor is operating at normallevels, C1 may indicate the processor is not executing instructions butmay return to an executing state quickly, C2 may indicate the processoris to maintain all software-visible information but may take longer toreturn to full executing state, C3 may indicate the processor is asleepbut keeps its cache coherent, C6 may indicate much deeper sleep statewhere caches are flushed, etc.

However, support for aggressive Operating System (OS) or Software (SW)driven power management is generally very minimal, especially from an OSperspective. Moreover, most current OS power management strategies tendnot to scale very well with multiple core systems from a processor powermanagement perspective, or the platform as a whole.

Accordingly, how the various power consumption states are utilized mayhave a direct impact on performance and/or power consumption of aprocessor.

BRIEF DESCRIPTION OF THE DRAWINGS

The detailed description is provided with reference to the accompanyingfigures. In the figures, the left-most digit(s) of a reference numberidentifies the figure in which the reference number first appears. Theuse of the same reference numbers in different figures indicates similaror identical items.

FIGS. 1, 9, and 10 illustrate block diagrams of embodiments of computingsystems, which may be utilized to implement various embodimentsdiscussed herein.

FIG. 2 illustrates a block diagram of portions of a processor core andother components of a computing system, according to an embodiment.

FIG. 3 illustrates a block diagram of power management architecture foran Android based system that may be used to implement one or moreembodiments discussed herein.

FIG. 4 illustrates a timing diagram according to an embodiment.

FIGS. 5-7 illustrate various graphs according to some embodiments.

FIG. 8 illustrates a suspend flow to dynamically choose power states,according to an embodiment.

DETAILED DESCRIPTION

In the following description, numerous specific details are set forth inorder to provide a thorough understanding of various embodiments.However, various embodiments of the invention may be practiced withoutthe specific details. In other instances, well-known methods,procedures, components, and circuits have not been described in detailso as not to obscure the particular embodiments of the invention.Further, various aspects of embodiments of the invention may beperformed using various means, such as integrated semiconductor circuits(“hardware”), computer-readable instructions organized into one or moreprograms (“software”), or some combination of hardware and software. Forthe purposes of this disclosure reference to “logic” shall mean eitherhardware, software, firmware, or some combination thereof. Also, the useof “instruction” and “micro-operation” (uop) is interchangeable asdiscussed herein.

Power management is crucial for mobile devices (such as phones, tablets,UMPC (Ultra-Mobile Personal Computer), laptop computers, etc.) and henceit is critical that such platforms are highly optimized from a power andperformance point of view. To this end, some embodiments provide powerconsumption reduction (e.g., in System on Chip (SOC) platforms) viapower state switching. Generally, an SOC refers to an integrated circuitchip or die that includes/integrates various components (such as one ormore components discussed herein with reference to the figures, such asone or more of: processor core(s), memory, networking logic, etc.) toprovide a system. For example, battery life of SOCs (e.g., running theAndroid™ OS or other operating systems used in mobile devices) may beincreased through dynamic power state switching. In an embodiment, thepower state of a device is dynamically switched between S0ix and S3during run-time.

Generally, “S0ix” refers to improved idle power state(s) achieved byplatform-level power management that is event driven (e.g., based on OSor software application input) instead of traditional idle power statethat is driven either by a user or based on a determination that aplatform has been idle for too long (based on a pre-programmed time). Insome embodiments, at least some of the power consumption statesdiscussed herein may be in accordance with or similar to those definedunder Advanced Configuration and Power Interface (ACPI) specification,Revision 5, December 2011. As discussed herein, “S3” generally refers toa power state such as standby, sleep, and/or suspend to Random AccessMemory (RAM), e.g., while the RAM remains powered to maintain datacorrectness.

In one embodiment, a processor includes logic (such as logic 120discussed with reference to the figures herein) to control whichspecific processor core(s) are to change power states based, at least inpart, on input from OS software and/or software application(s).Moreover, the ability to control the level of power states may be usedto optimize platform power consumption in response to variousdeterminations such as based on the workload, scenario, usage, etc.Furthermore, at least some OS operations discussed herein may beinterchangeably performed by software applications, firmware, etc.

The techniques discussed herein may be used in any type of a processorwith performance state settings, such as the processors discussed withreference to FIGS. 1 and 9-10. More particularly, FIG. 1 illustrates ablock diagram of a computing system 100, according to an embodiment ofthe invention. The system 100 may include one or more processors 102-1through 102-N (generally referred to herein as “processors 102” or“processor 102”). The processors 102 may communicate via aninterconnection network or bus 104. Each processor may include variouscomponents some of which are only discussed with reference to processor102-1 for clarity. Accordingly, each of the remaining processors 102-2through 102-N may include the same or similar components discussed withreference to the processor 102-1.

In an embodiment, the processor 102-1 may include one or more processorcores 106-1 through 106-M (referred to herein as “cores 106” or moregenerally as “core 106”), a shared cache 108, a router 110, and/or aprocessor control logic or unit 120. The processor cores 106 may beimplemented on a single integrated circuit (IC) chip. Moreover, the chipmay include one or more shared and/or private caches (such as cache108), buses or interconnections (such as a bus or interconnectionnetwork 112), memory controllers (such as those discussed with referenceto FIGS. 9-10), or other components.

In one embodiment, the router 110 may be used to communicate betweenvarious components of the processor 102-1 and/or system 100. Moreover,the processor 102-1 may include more than one router 110. Furthermore,the multitude of routers 110 may be in communication to enable datarouting between various components inside or outside of the processor102-1.

The shared cache 108 may store data (e.g., including instructions) thatare utilized by one or more components of the processor 102-1, such asthe cores 106. For example, the shared cache 108 may locally cache datastored in a memory 114 for faster access by components of the processor102. In an embodiment, the cache 108 may include a mid-level cache (suchas a level 2 (L2), a level 3 (L3), a level 4 (L4), or other levels ofcache), a last level cache (LLC), and/or combinations thereof. Moreover,various components of the processor 102-1 may communicate with theshared cache 108 directly, through a bus (e.g., the bus 112), and/or amemory controller or hub. As shown in FIG. 1, in some embodiments, oneor more of the cores 106 may include a level 1 (L1) cache 116-1(generally referred to herein as “L1 cache 116”).

In one embodiment, the control unit 120 controls which specificprocessor core(s) are to change power states (e.g., between S3 and S0ixstates) based, at least in part, on input from OS software and/orsoftware application(s) (e.g., that may be stored in the memory 114).Moreover, the ability to control the level of power states may be usedto optimize platform power consumption in response to variousdeterminations such as based on the workload, scenario, usage, etc.Furthermore, at least some OS operations discussed herein may beinterchangeably performed by software applications, firmware, etc.

FIG. 2 illustrates a block diagram of portions of a processor core 106and other components of a computing system, according to an embodimentof the invention. In one embodiment, the arrows shown in FIG. 2illustrate the flow direction of instructions through the core 106. Oneor more processor cores (such as the processor core 106) may beimplemented on a single integrated circuit chip (or die) such asdiscussed with reference to FIG. 1. Moreover, the chip may include oneor more shared and/or private caches (e.g., cache 108 of FIG. 1),interconnections (e.g., interconnections 104 and/or 112 of FIG. 1),control units, memory controllers, or other components.

As illustrated in FIG. 2, the processor core 106 may include a fetchunit 202 to fetch instructions (including instructions with conditionalbranches) for execution by the core 106. The instructions may be fetchedfrom any storage devices such as the memory 114 and/or the memorydevices discussed with reference to FIGS. 9-10. The core 106 may alsoinclude a decode unit 204 to decode the fetched instruction. Forinstance, the decode unit 204 may decode the fetched instruction into aplurality of uops (micro-operations).

Additionally, the core 106 may include a schedule unit 206. The scheduleunit 206 may perform various operations associated with storing decodedinstructions (e.g., received from the decode unit 204) until theinstructions are ready for dispatch, e.g., until all source values of adecoded instruction become available. In one embodiment, the scheduleunit 206 may schedule and/or issue (or dispatch) decoded instructions toan execution unit 208 for execution. The execution unit 208 may executethe dispatched instructions after they are decoded (e.g., by the decodeunit 204) and dispatched (e.g., by the schedule unit 206). In anembodiment, the execution unit 208 may include more than one executionunit. The execution unit 208 may also perform various arithmeticoperations such as addition, subtraction, multiplication, and/ordivision, and may include one or more an arithmetic logic units (ALUs).In an embodiment, a co-processor (not shown) may perform variousarithmetic operations in conjunction with the execution unit 208.

Further, the execution unit 208 may execute instructions out-of-order.Hence, the processor core 106 may be an out-of-order processor core inone embodiment. The core 106 may also include a retirement unit 210. Theretirement unit 210 may retire executed instructions after they arecommitted. In an embodiment, retirement of the executed instructions mayresult in processor state being committed from the execution of theinstructions, physical registers used by the instructions beingde-allocated, etc.

The core 106 may also include a bus unit 214 to enable communicationbetween components of the processor core 106 and other components (suchas the components discussed with reference to FIG. 1) via one or morebuses (e.g., buses 104 and/or 112). The core 106 may also include one ormore registers 216 to store data accessed by various components of thecore 106 (such as values related to power consumption state settings).

Furthermore, even though FIG. 1 illustrates the control unit 120 to becoupled to the core 106 via interconnect 112, in various embodiments thecontrol unit 120 may be located elsewhere such as inside the core 106,coupled to the core via bus 104, etc.

FIG. 3 illustrates a block diagram of power management architecture foran Android based system that may be used to implement one or moreembodiments discussed herein. More specifically, the Android powermanagement infrastructure is split across the User space 302 and Kernellayer 304. Wake locks may form a critical part of the framework. A “WakeLock” can be defined as request by the application(s) 306 and/orservice(s) to request one or more of the platform resources (such as CPU(Central Processing Unit—also referred to herein interchangeably as“processor”), display, etc.), e.g., to stay powered on or awake (hence,a “wake lock” may also be referred to herein interchangeably as a “awakerequest”).

The Android Framework exposes power management to services and/orapplications through a Power Manager class. All calls for PowerManagement go through the Android runtime Power Manager API (ApplicationProgramming Interface) to acquire and release wake locks. Kernel driversmay register with the Android Power Manager driver so that they arenotified immediately prior to power down or after power up—drivers canregister early_suspend ( ) and late_resume( ) handlers, which are calledwhen the display power state changes. The Android OS currently supportsonly suspend to RAM (a.k.a., S3) state (e.g., while power is supplied toRAM to maintain data correctness). This builds upon the traditionalLinux® power management infrastructure and uses concepts of wake locks(i.e., application hints about platform resource usage) to achieve S3.The power management infrastructure in Android requires thatapplications and services request CPU resources with “wake locks”through the Android application framework 308 and/or native Linuxlibraries. If there are no active wake locks, Android will suspend thesystem to S3.

While the current S3 implementation in Android helps reduce overallplatform power, this does not satisfy applications that require alwaysconnected behavior. Applications like instant messengers, VoIP (Voiceover Internet Protocol), etc. need to send “keep alive” messages tomaintain their active sessions. Entering S3 will result in freezingthese applications and therefore connections can timeout and thesessions will have to be re-established on resume. To keep theseapplications active and still achieve reasonable power numbers, S0ix orActive Idle states feature (also known as Connected Standby in recentIntel®-based Microsoft Windows® platforms) can be used from the platformperspective in some embodiments. As discussed herein, S0ix and ActiveIdle states are used interchangeably.

Some embodiments use S0ix during an idle window to allow the platform tostay in the lowest power state as long as reasonably possible. In thisstate, all platform components are transitioned to an appropriate lowerpower state (e.g., CPU is in Cx state, memory is in Self Refresh, othercomponents are clock or power gated, etc.) in accordance with anembodiment. As soon a timer or wake event occurs, the platform movesinto an “Active” state (e.g., only the components that are needed areturned on, keeping everything else still in low power state). Hence, ontrue idleness, CPU C-states may be extended to devices, and the rest ofthe platform, e.g., pushing the platform aggressively to S0ix states.

Referring to FIG. 4, a timing diagram is shown for aligning platformpower states with CPU during device idleness at S0ix, according to anembodiment. As shown, various components such as memory, controllers,clocks, Voltage Regulator(s) (VRs), and other platform components arealigned during an idle window with the CPU, e.g., based on an OS timer(e.g., HPET (High Performance Event Timer)) after some active window,followed by an optional policy windows. Once the idle window ends, andafter an optional warm-up window, the active state resumes.

FIG. 5 is a graph of average power versus time illustrating comparisonof how S0ix states impact platform power states, according to anembodiment. More specifically, FIG. 5 illustrates how the impact of S0ixstates compares with traditional (e.g., ACPI-based) power management. Asshown, even after applications acquire wake locks to prevent S3, OSPower Management (OSPM) driver may still opportunistically causeinitiation of S0i3 (which may be more generally referred to herein asS0ix), which may transition afterwards to S3, e.g., when no wake locksremain.

In some implementations, the OS for a smart phone or tablet mayimplement both S0ix and S3. S0ix may be used in very specific scenarioslike low power audio playback (where the entire platform except theaudio cluster can be put into a low power mode), or display self-refresh(where only the display panel can be kept on, and entire SOC can be putinto lowest possible power state). S0ix has very low entry/exitlatencies at about 2 ms, whereas S3 entry/exit latencies range in theorder of 100 s of milliseconds (since devices must be suspended,applications must be frozen, etc.). For example, in idle scenarios, whenthe phone is in idle standby with 3G and/or WLAN (Wireless Local AreaNetwork) connected), the platform power can still be around 14 mW onsome Android based phones.

Ideally, there should be no wakes on the platform that can cause thephone to exit out of S3 state and into S0 state (where S0 refers to theoperating/working state). However, in real usage scenarios, there may bea lot of wakes that happen when background data is enabled on a realnetwork. Most of these wakes may be due to applications waking theplatform (such as maps, Google® GSF (Google Services Framework), etc.)or applications performing push from network (such as Google+™,etc.).These wakes could happen every 30 sec (e.g., as seen on real livenetwork with WIFI (Wireless Fidelity) on).

To this end, some embodiments reduce platform power consumption byaggressively invoking and maintaining S0ix state in mobile devices (suchas phones, tablets, UMPC (Ultra-Mobile Personal Computer), laptopcomputers, etc.). Moreover, entering/exiting S3 too frequently may notalways provide a net power benefit, e.g., due to the fact that S3 canhave higher transition cost of doing full suspend/resume (around 2seconds) as compared to S0i3 (around 2 ms). In fact, in some situations,entering/exiting S3 too frequently can actually hurt, leading to ahigher consumption when selecting S3 if there are frequent wakeshappening on the platform. In such scenarios, state S0ix is enteredrather than S3 in an embodiment (even if Android power managementattempts to enter S3).

In some implementations, there may be periodic events due to differentapplications (such as Google Services, Google Sync, Maps, etc.) thatcause the platform to wake up periodically from standby (or S3). Forexample, some phones may wake up as many as 250 times in an hour (i.e.,4 wakes a minute, or one every 15 seconds). However, as the number ofwakes increases, entering S0i3 instead of S3 becomes more and morebeneficial. This is illustrated in FIG. 6 which shows platform currentdraw (in mA) versus the number of wakes (e.g., per second) changes forS0i3/S3 threshold on a sample platform, according to some embodiments.

As shown in FIG. 6, there is a threshold point (a threshold number ofwakes per second) at which S0ix becomes more beneficial than S3 for theplatform in terms of power consumption. As can be seen, the higher thenumber of wakes on the platform, the more beneficial it is to do S0i3instead of S3. This can sometimes allow for 50% to 60% gain in standbybattery life.

Referring to FIG. 7, a graph of the average power consumption (e.g., inmA) of S0ix/S3 plotted against the frequency of wakes on the platform isillustrated, according to an embodiment. Based on the entry/exit latencyvalues of S0ix and S3, it can be seen that there is a threshold wherethere is benefit in picking low-latency S0ix rather than S3.

In some embodiments, the power characterization of S3 profiling isgiving by the following formula:E _(S3)( T _(th))=Ū·Ī _(ST) ·T _(S3) +Ū·Ī _(S3)·( T _(th) −T _(S3))  (1)where:

E_(S3) is defined as the average of power consumption during period T_(th);

T _(th) is defined as the cross-point between S3 and S0i3 curves givenabove;

Ī_(ST) is defined as the average of current consumption during asuspend/resume transition;

T _(S3) is defined as the delay required for the device to go throughthe whole suspend patch; and

Ī_(S3) is defined as the average of power consumption in S3.

Also, the power characterization of S0i3 profiling is giving by thefollowing formula in accordance with some embodiments:E _(S0i3)(T _(th))=Ū·Ī _(S0i3) ·T _(th)   (2)where:

E_(S0i3) is defined as the power consumption during T _(th); and

Ī_(S0i3) is defined as the current consumption in S0i3.

Matching the two formulae (1 and 2) given above, may be determined as:

$T_{th} = {{\overset{\_}{T}}_{S\; 3} \times \frac{{\overset{\_}{I}}_{ST} - {\overset{\_}{I}}_{S\; 3}}{{\overset{\_}{I}}_{S\; 0i\; 3} - {\overset{\_}{I}}_{S\; 3}}}$

In accordance with some embodiments, if the next wake is beyond about a60 second window (e.g., as determined as per the calculation above), itis beneficial to enter S3 state; whereas, if the next wake is withinabout 60 seconds, picking S0i3 state is most beneficial from a powerconsumption point of view.

FIG. 8 illustrates a sample suspend flow 800 (e.g., for an Android OS)according to an embodiment. Flow 800 is used to dynamically choose S0ixversus S3 in some embodiments. In some embodiments, various componentsdiscussed with reference to FIGS. 1-7 and 9-10 may be utilized toperform one or more of the operations discussed with reference to FIG.8. For example, the control unit 120 may be used to control powerconsumption states of one or more processor cores 106 and/or perform oneor more of the operations discussed with reference to flow 800.

As illustrated, whenever a wake lock is taken or released 802, thekernel interface 804 for grabbing a wake lock is accessed at 806. Theuser mode policy manager for Android will know what locks are held andwhen there are no full wake locks the power management service willinform the kernel to turn off the display by accessing the/sys/power/state interface, by writing “mem” to it. To turn on thedisplay, the PM (Power Management) service writes “on” to/sys/power/state. This is illustrated in FIG. 8. As it can be seen,there are two main kernel work queues: (1) early suspend work queue(shown on the left portion of the figure including 810-814): this isinvoked from the main kernel path when “mem” is written into/sys/power/state at 818 (this work queue is responsible for calling alldrivers that have registered early_suspend notifiers); and (2) suspendwork queue (shown on the right portion of the figure including 806 and820-822): when there are no wake locks held in the platform, this workqueue finally freezes application processes, and invokes the pm_suspendpath in the kernel.

Moreover, early suspend happens when the user mode writes “mem” to/sys/power/state at 818. For example, whenever the user mode turns offthe screen, the registered early suspend callbacks are called at 812.The kernel keeps a list of wake_locks held. When the wake lock listtransitions from non-empty to empty pm_suspend is called at 822. This isa Linux platform state where all applications are frozen, drivers havetheir suspend entry points called, and interrupts are turned off Theplatform will not exit this state except on external event, e.g., GPIO(General Purpose Input/Output), interrupt generated from an RTC (RealTime Clock), or an external interrupt (an incoming call for example).All non-wake-up hardware is expected to enter its lowest power state toreduce power consumption. Hardware that can generate a wake up interruptis expected to go into a low power mode as well, but still functionenough to wake the system out of the suspend state.

Some embodiments are implemented within the Android power managementinfrastructure, and more specifically within the Linux Kernel. Forexample, at operation 822, a new embodiment is provided to extend thefunctionality of an alarm driver to expose information of when the nextalarm is expected to be triggered. This newly added function is used bya PMU (Power Management Unit) driver, e.g., along with a programmedthreshold value, to determine if the platform should enter S0ix or S3.In this way, a suspend is authorized only when the next alarm expiry ishigher than the break event. The updated kernel PM suspend path (asshown in FIG. 8) is able to dynamically pick S0ix or S3 depending on atunable parameter (which may be set at boot time or run time in variousembodiments).

FIG. 9 illustrates a block diagram of a computing system 900 inaccordance with an embodiment of the invention. The computing system 900may include one or more central processing unit(s) (CPUs) 902 orprocessors that communicate via an interconnection network (or bus) 904.The processors 902 may include a general purpose processor, a networkprocessor (that processes data communicated over a computer network903), or other types of a processor (including a reduced instruction setcomputer (RISC) processor or a complex instruction set computer (CISC)).Moreover, the processors 902 may have a single or multiple core design.The processors 902 with a multiple core design may integrate differenttypes of processor cores on the same integrated circuit (IC) die. Also,the processors 902 with a multiple core design may be implemented assymmetrical or asymmetrical multiprocessors. In an embodiment, one ormore of the processors 902 may be the same or similar to the processors102 of FIG. 1. For example, one or more of the processors 902 mayinclude the control unit 120 discussed with reference to FIGS. 1-8.Also, the operations discussed with reference to FIGS. 1-8 may beperformed by one or more components of the system 900.

A chipset 906 may also communicate with the interconnection network 904.The chipset 906 may include a memory control hub (MCH) 908. The MCH 908may include a memory controller 910 that communicates with a memory 912(which may be the same or similar to the memory 114 of FIG. 1). Thememory 912 may store data, including sequences of instructions, that maybe executed by the CPU 902, or any other device included in thecomputing system 900. In one embodiment of the invention, the memory 912may include one or more volatile storage (or memory) devices such asrandom access memory (RAM), dynamic RAM (DRAM), synchronous DRAM(SDRAM), static RAM (SRAM), or other types of storage devices.Nonvolatile memory may also be utilized such as a hard disk. Additionaldevices may communicate via the interconnection network 904, such asmultiple CPUs and/or multiple system memories.

The MCH 908 may also include a graphics interface 914 that communicateswith a display device 916. In one embodiment of the invention, thegraphics interface 914 may communicate with the display device 916 viaan accelerated graphics port (AGP). In an embodiment of the invention,the display 916 (such as a flat panel display) may communicate with thegraphics interface 914 through, for example, a signal converter thattranslates a digital representation of an image stored in a storagedevice such as video memory or system memory into display signals thatare interpreted and displayed by the display 916. The display signalsproduced by the display device may pass through various control devicesbefore being interpreted by and subsequently displayed on the display916.

A hub interface 918 may allow the MCH 908 and an input/output controlhub (ICH) 920 to communicate. The ICH 920 may provide an interface toI/O device(s) that communicate with the computing system 900. The ICH920 may communicate with a bus 922 through a peripheral bridge (orcontroller) 924, such as a peripheral component interconnect (PCI)bridge, a universal serial bus (USB) controller, or other types ofperipheral bridges or controllers. The bridge 924 may provide a datapath between the CPU 902 and peripheral devices. Other types oftopologies may be utilized. Also, multiple buses may communicate withthe ICH 920, e.g., through multiple bridges or controllers. Moreover,other peripherals in communication with the ICH 920 may include, invarious embodiments of the invention, integrated drive electronics (IDE)or small computer system interface (SCSI) hard drive(s), USB port(s), akeyboard, a mouse, parallel port(s), serial port(s), floppy diskdrive(s), digital output support (e.g., digital video interface (DVI)),or other devices.

The bus 922 may communicate with an audio device 926, one or more diskdrive(s) 928, and a network interface device 930 (which is incommunication with the computer network 903). Other devices maycommunicate via the bus 922. Also, various components (such as thenetwork interface device 930) may communicate with the MCH 908 in someembodiments of the invention. In addition, the processor 902 and the MCH908 may be combined to form a single chip. Furthermore, the graphicsaccelerator 916 may be included within the MCH 908 in other embodimentsof the invention.

Furthermore, the computing system 900 may include volatile and/ornonvolatile memory (or storage). For example, nonvolatile memory mayinclude one or more of the following: read-only memory (ROM),programmable ROM (PROM), erasable PROM (EPROM), electrically EPROM(EEPROM), a disk drive (e.g., 928), a floppy disk, a compact disk ROM(CD-ROM), a digital versatile disk (DVD), flash memory, amagneto-optical disk, or other types of nonvolatile machine-readablemedia that are capable of storing electronic data (e.g., includinginstructions).

FIG. 10 illustrates a computing system 1000 that is arranged in apoint-to-point (PtP) configuration, according to an embodiment of theinvention. In particular, FIG. 10 shows a system where processors,memory, and input/output devices are interconnected by a number ofpoint-to-point interfaces. The operations discussed with reference toFIGS. 1-9 may be performed by one or more components of the system 1000.

As illustrated in FIG. 10, the system 1000 may include severalprocessors, of which only two, processors 1002 and 1004 are shown forclarity. The processors 1002 and 1004 may each include a local memorycontroller hub (MCH) 1006 and 1008 to enable communication with memories1010 and 1012. The memories 1010 and/or 1012 may store various data suchas those discussed with reference to the memory 912 of FIG. 9.

In an embodiment, the processors 1002 and 1004 may be one of theprocessors 902 discussed with reference to FIG. 9. The processors 1002and 1004 may exchange data via a point-to-point (PtP) interface 1014using PtP interface circuits 1016 and 1018, respectively. Also, theprocessors 1002 and 1004 may each exchange data with a chipset 1020 viaindividual PtP interfaces 1022 and 1024 using point-to-point interfacecircuits 1026, 1028, 1030, and 1032. The chipset 1020 may furtherexchange data with a graphics circuit 1034 via a graphics interface1036, e.g., using a PtP interface circuit 1037.

At least one embodiment of the invention may be provided within theprocessors 1002 and 1004. For example, the control unit 120 of FIGS. 1-9may be located within the processors 1002 and 1004. Other embodiments ofthe invention, however, may exist in other circuits, logic units, ordevices within the system 1000 of FIG. 10. Furthermore, otherembodiments of the invention may be distributed throughout severalcircuits, logic units, or devices illustrated in FIG. 10.

The chipset 1020 may communicate with a bus 1040 using a PtP interfacecircuit 1041. The bus 1040 may communicate with one or more devices,such as a bus bridge 1042 and I/O devices 1043. Via a bus 1044, the busbridge 1042 may communicate with other devices such as a keyboard/mouse1045, communication devices 1046 (such as modems, network interfacedevices, or other communication devices that may communicate with thecomputer network 903), audio I/O device 1047, and/or a data storagedevice 1048. The data storage device 1048 may store code 1049 that maybe executed by the processors 1002 and/or 1004.

In various embodiments of the invention, the operations discussedherein, e.g., with reference to FIGS. 1-10, may be implemented ashardware (e.g., logic circuitry), software, firmware, or combinationsthereof, which may be provided as a computer program product, e.g.,including (e.g., a non-transitory) machine-readable or computer-readablemedium having stored thereon instructions (or software procedures) usedto program a computer to perform a process discussed herein. Themachine-readable medium may include a storage device such as thosediscussed with respect to FIGS. 1-10.

Additionally, such computer-readable media may be downloaded as acomputer program product, wherein the program may be transferred from aremote computer (e.g., a server) to a requesting computer (e.g., aclient) by way of data signals embodied in a carrier wave or otherpropagation medium via a communication link (e.g., a bus, a modem, or anetwork connection).

Reference in the specification to “one embodiment,” “an embodiment,” or“some embodiments” means that a particular feature, structure, orcharacteristic described in connection with the embodiment(s) may beincluded in at least an implementation. The appearances of the phrase“in one embodiment” in various places in the specification may or maynot be all referring to the same embodiment.

Also, in the description and claims, the terms “coupled” and“connected,” along with their derivatives, may be used. In someembodiments of the invention, “connected” may be used to indicate thattwo or more elements are in direct physical or electrical contact witheach other. “Coupled” may mean that two or more elements are in directphysical or electrical contact. However, “coupled” may also mean thattwo or more elements may not be in direct contact with each other, butmay still cooperate or interact with each other.

Thus, although embodiments of the invention have been described inlanguage specific to structural features and/or methodological acts, itis to be understood that claimed subject matter may not be limited tothe specific features or acts described. Rather, the specific featuresand acts are disclosed as sample forms of implementing the claimedsubject matter.

The invention claimed is:
 1. An apparatus comprising: control logic, thecontrol logic at least partially comprising hardware logic, to cause aprocessor to enter a first low power consumption state instead of asecond low power consumption state based on a threshold time periodbetween a first wake event and a second wake event, wherein the firstlow power consumption state is to consume more power than the second lowpower consumption state, wherein the first wake event or the second wakeevent are to each correspond to one of a plurality of awake requests,wherein the processor is to enter the first low power consumption statebased at least in part on one of the plurality of awake requests,wherein each of the plurality of awake requests is to cause preventionof entry into the second low power consumption state for as long as theone or more awake requests are active.
 2. The apparatus of claim 1,wherein each of the plurality of awake requests causes one or moreplatform resources to stay powered on or awake.
 3. The apparatus ofclaim 1, wherein the plurality of awake requests are to be generated inresponse to one or more requests from one of an application and aservice.
 4. The apparatus of claim 1, wherein the first wake event is tocorrespond to a first one of the plurality of awake requests and thesecond wake event is to correspond to a second one of the plurality ofawake requests.
 5. The apparatus of claim 1, wherein the control logicis to cause the processor to enter the first low power consumption statebased on a source of the first wake event or second wake event.
 6. Theapparatus of claim 1, further comprising memory to store operatingsystem software, wherein the operating system software is to trigger thefirst wake event or second wake event.
 7. The apparatus of claim 6,wherein the operating system software is to trigger the first wake eventor the second wake event based on a timer.
 8. The apparatus of claim 1,wherein the control logic is to determine whether the processor is toenter the first low power consumption state based on one or more ofworkload, and usage conditions in a platform that comprises theprocessor.
 9. The apparatus of claim 1, wherein the second low powerconsumption state comprises an idle state or a standby state.
 10. Theapparatus of claim 1, further comprising memory to store applicationsoftware, wherein the application software is to trigger the first wakeevent or second wake event.
 11. The apparatus of claim 10, wherein theapplication software is to trigger the first or second wake event basedon a timer.
 12. The apparatus of claim 1, wherein the first or secondwake event is to indicate resumption from a platform idle state.
 13. Theapparatus of claim 1, wherein the processor is to comprise a pluralityof processor cores, wherein at least the first wake event or the secondwake event is to cause at least one of the plurality of the processorcores to wake from the first or second low power consumption state. 14.The apparatus of claim 1, wherein the threshold time period is about 60seconds.
 15. A method comprising: determining whether a threshold timeperiod exists between a first wake event and a second wake event;causing a processor to enter a first low power consumption state insteadof a second low power consumption state based on the existence of thethreshold time period, wherein the first low power consumption state isto consume more power than the second low power consumption state,wherein the processor enters the first low power consumption state basedon one of the plurality of awake requests, wherein each of the pluralityof awake requests causes prevention of entry into the second low powerconsumption state for as long as the one or more awake requests areactive.
 16. The method of claim 15, further comprising determiningwhether one or more awake requests exist, wherein the first wake eventcorresponds to the first one of the one or more awake requests and thesecond wake event corresponds to a second one of the one or more awakerequests.
 17. The method of claim 15, further comprising causing theprocessor to enter the first low power consumption state based on asource of the first wake event or second wake event.
 18. Anon-transitory computer-readable medium to store instructions that whenexecuted by a processor cause the processor to: determine whether athreshold time period exists between a first wake event and a secondwake event; cause the processor to enter a first low power consumptionstate instead of a second low power consumption state based on theexistence of the threshold time period, wherein the first low powerconsumption state is to consume more power than the second low powerconsumption state, wherein the first wake event or the second wake eventare to each correspond to one of a plurality of awake requests, whereinthe processor is to enter the first low power consumption state based onone of the plurality of awake requests, wherein each of the plurality ofawake requests is to cause prevention of entry into the second low powerconsumption state for as long as the one or more awake requests areactive.
 19. The non-transitory computer-readable medium of claim 18,wherein each of the plurality of awake requests is to cause one or moreplatform resources to stay powered on or awake.
 20. The non-transitorycomputer-readable medium of claim 18, wherein the instructions are tocause the processor to generate one or more awake requests in responseto one or more requests from one of an application and a service. 21.The non-transitory computer-readable medium of claim 18, wherein theinstructions are to cause the processor to enter the first low powerconsumption state based on a source of the first wake event or secondwake event.
 22. The non-transitory computer-readable medium of claim 18,wherein the non-transitory computer-readable memory is to storeoperating system software, wherein the operating system software is totrigger the first wake event or second wake event.
 23. Thenon-transitory computer-readable medium of claim 22, wherein theoperating system software is to trigger the first wake event or thesecond wake event based on a timer.
 24. The non-transitorycomputer-readable medium of claim 18, wherein the instructions are tocause the processor to determine whether the processor is to enter thefirst low power consumption state based on one or more of workload, andusage conditions in a platform that comprises the processor.
 25. Thenon-transitory computer-readable medium of claim 18, wherein the secondlow power consumption state comprises an idle state or a standby state.